1. Field of the Invention
The invention relates to a sewing installation for the production of a piped pocket opening on a cloth workpiece.
2. Background Art
U.S. Pat. No. 3,747,545 teaches a sewing apparatus for the formation of a piped pocket opening on a cloth workpiece which comprises a working plate, a two-needle sewing machine disposed on the working plate, and a workpiece advancing device for the transport of the workpiece in a Y-direction on the working plate. Furthermore, a knife is available for the production of a straight incision in the Y-direction in the workpiece during transport in the Y-direction. A cutout, which extends in the Y-direction, is formed in the working plate. Underneath the working plate, provision is made for a cutting device for the production of corner cuts, the cutting device comprising two corner cutting knives. Each corner cutting knife consists of two blades. For the production of so-called diagonal corner cuts which are necessary in diagonal pocket openings, the corner cutting knives are of pivotal design. This kind of adjustment of the corner cutting knives permits only a comparatively restricted influence on the feasible corner cuts; therefore, this type of knife adjustment has not been successful in practice. Moreover the structure is very complicated. Any adjustment of the corner cutting knives can be triggered only in constructionally defined stages. The known cutting device is accompanied with considerable requirements in terms of assembly, adjustment and fabrication.
U.S. Pat. No. 3,820,481 teaches a sewing apparatus for the production of a piped pocket opening on a cloth workpiece, the pocket opening being alternatively straight or diagonal. It comprises a cutting device with corner cutting knives which consist of two individual knives. Variability of the angles of the corner cuts at the respective end of the pocket opening is attained in that on the one hand the corner cutting knives are rotatable in defined given stages and in that moreover the two knives of a corner cutting knife penetrate into the workpiece by varying depths. The known design is constructionally complicated and correspondingly costly. Assembly and adjustment are also accompanied with considerable time expenditure. Moreover, the angles of the corner cuts can only be triggered in given stages. Since these knives penetrate into the workpiece by varying depths, the cutting lengths in the corner cut depend on the material.
U.S. Pat. No. 5,400,731 teaches a sewing system for the production of a piped pocket opening on a cloth workpiece, which fundamentally corresponds to that according to U.S. Pat. No. 3,820,481 described above. In this case, however, rotation of the knives takes place by means of stepping motors that can be triggered continuously, and the cutting motion of the knives is effected by pneumatically actuated piston-cylinder drives. The drawbacks are fundamentally the same as described above.
A sewing apparatus is known from DE 42 24 034 A1, having a cutting device for the production of corner cuts. The corner cutting knives are drivable by means of electric motors, each knife of a corner cutting knife being adjustable to varying cutting strokes and angles for corner cuts of varying angles and cutting lengths to be carried out. Correspondingly, each corner cutting knife is provided with four motors so that the cutting device, which comprises two corner cutting knives, has a complicated design. In this case, too, there is the drawback that the cutting lengths in the corner cut depend on the material due to the varying depths of penetration of the knives.